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<title>Berkeley DB Reference Guide: Retrieved key/data permanence for C/C++</title>
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<td><b><dl><dt>Berkeley DB Reference Guide:<dd>Access Methods</dl></b></td>
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<p align=center><b>Retrieved key/data permanence for C/C++</b></p>
<p>When using the non-cursor Berkeley DB calls to retrieve key/data items under
the C/C++ APIs (for example, <a href="../../api_c/db_get.html">DB-&gt;get</a>), the memory to which the
pointer stored into the <a href="../../api_c/dbt_class.html">DBT</a> refers is only valid until the next
call to Berkeley DB using the <a href="../../api_c/db_class.html">DB</a> handle.  (This includes <b>any</b>
use of the returned <a href="../../api_c/db_class.html">DB</a> handle, including by another thread of
control within the process.  For this reason, when multiple threads are
using the returned <a href="../../api_c/db_class.html">DB</a> handle concurrently, one of the
<a href="../../api_c/dbt_class.html#DB_DBT_MALLOC">DB_DBT_MALLOC</a>, <a href="../../api_c/dbt_class.html#DB_DBT_REALLOC">DB_DBT_REALLOC</a> or <a href="../../api_c/dbt_class.html#DB_DBT_USERMEM">DB_DBT_USERMEM</a>
flags must be specified with any non-cursor <a href="../../api_c/dbt_class.html">DBT</a> used for key or
data retrieval.)</p>
<p>When using the cursor Berkeley DB calls to retrieve key/data items under the
C/C++ APIs (for example, <a href="../../api_c/dbc_get.html">DBcursor-&gt;get</a>), the memory to which the
pointer stored into the <a href="../../api_c/dbt_class.html">DBT</a> refers is only valid until the next
call to Berkeley DB using the <a href="../../api_c/dbc_class.html">DBC</a> handle returned by <a href="../../api_c/db_cursor.html">DB-&gt;cursor</a>.</p>
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